Here is an article describing the potential for under-withholding throughout 2018, due to the Tax Cuts and Jobs Act, which would result in an individual having to pay the IRS a year from now when they complete their 2018 return instead of receiving a refund.
The IRS withholding calculator,
https://www.irs.gov/individuals/irs-withholding-calculator, is not yet updated to account for the changes to the tax law.
We thought you would be interested in the following article found on MSN from The Washington Post: Check your paycheck -- you might be getting too much money
“We suggest that people look at their withholdings every year, but most don’t,” said IRS spokesman Eric Smith. “But if ever there was a year to look at your withholdings, this is the year. Your current return is a road map of your tax situation.”